The present invention is directed to a station for piling, separating and creating batches which consist of a predetermined number of piled plate-like workpieces, such as sheets of paper or cardboard or even fiat-folded cardboard boxes. The station is located downstream a station for counting and carrying the workpieces coming out of a processing machine.
In the station for counting and carrying, the sheets are successively forwarded along a distribution conveyor in front of a counting device which includes, for instance, a photoelectric cell, and then to a piling station which comprises a collecting device, such as a hopper, in which the sheets are aligned into regular piles. A specific form of mechanism is required in order to adapt the growing pile to the collector. A known mechanism enables the conveyor to be raised in close connection with the growing pile, whereas the most standard so-called freely dropping mechanism forces the sheets to land on a table with alternate vertical movement, which table descends at a speed of the growing pile. Once the number of sheets which make up a batch is reached, a problem of proper ejection of the batch or pile and removal of this batch without stopping the machine will occur.
This type of piling station is described in French Patent No. 2,348,882 and comprises a plurality of parallel L-shaped fingers which make up a separator, normally arranged horizontally and rotatably at one of its ends on a movable carriage. The separator is for temporarily receiving sheets dropping onto the top of the previous batch which is in the process of being removed by a conveyor. The station comprises, moreover, a second plurality of parallel T-shaped fingers connected by a shaft, thus making up a table which can be moved vertically through the conveyor in order to carry the sheets temporarily piled on the separator and to deliver them onto the conveyor during the time in which the separator is withdrawn in order to take up an oblique position and gets back to its resting position on top of the pile being built up on the conveyor. When the next batch is built up, the separator again descends in order to collect the next sheet. However, the maximum number of sheets belonging to such a batch depends on the maximal raising angle of the separator, which is necessarily little with regard to the mechanical stresses that exist.
A station or device described in U.S. Pat. No. 4,311,475, whose disclosure is incorporated herein by reference thereto and which claims priority from the same Japanese Application as French Published Application 2,445,563, comprises a hopper closed at the bottom by a vertically movable table, on which table the aligned sheets will pile up. When a predetermined number of sheets is reached, a rear finger lands on the batch in order to separate the batch from the next sheets and the batch then descends together with the table until the table reaches a level for a removal or ejection conveyor. A pusher moves the batch laterally toward the removal conveyor, the upper sheets being held at a rear side or edge by the finger and at a forward edge by the batch for the time the pusher requires to shift the batch from the table onto the conveyor and then to retract. The table is then raised in order to receive the upper sheets. A second finger is movable vertically and parallel with the first finger, which is already in the resting position for separating the next batch.
However, the table has to have a surface lower than the surface of the sheets. Moreover, this station requires a complex device for shifting in phase opposition two separating fingers.
A station is described in U.S. Pat. No. 4,359,218, whose disclosure is incorporated herein by reference thereto and which was the basis for French Published Application 2,511,352. In this station, sheets are accumulated on a pile carried by a table movable downward inside a hopper. As soon as a predetermined number of sheets is reached, a plate or interrupter bar moves from the front of the hopper over a short distance on the top of the pile. The table which carries the pile continues to move downward with regard to the interrupter so that a space is created, within which supporting arms are then inserted. The interrupter can then be retracted, and the arms will carry the accumulation of the next sheets. The batch is then lowered by the movable table onto an ejecting belt carrier or conveyor. The empty table then is raised and lifts the new pile by passing between the supporting arms. These arms are then retracted and are ready for a new cycle. However, the control mechanism for the interruption plate is rather complex in coordination with the movement of the supporting arms.
U.S. Pat. No. 5,160,129, whose disclosure is incorporated herein by reference thereto and which was the basis for European Published Application 0 529 708, describes a piling station specifically foreseen for flat-folded cardboard boxes at the end of a folding and gluing process, but whose certain flaps may be turned up. In this station, the sheets carried by the upstream distributing conveyor are sent into a hopper against a front stop by two ejecting or firing rollers, which are horizontal and parallel in a rear vertical plane. The sheets drop aligned on top of the pile that is growing on a hoisting table which descends as the pile grows.
When a batch is built up, a separator, which is situated at the front of the hopper and which consists of a plurality of forks connected by a crossbar movable along a first vertical toothed rack and a second horizontal toothed rack comes to lay on top of the batch in order to collect the next sheets. The table then descends until it reaches a level of the removing conveyor on which the batch is transferred by a pusher. The empty table then raises to take care of the new pile which is being accumulated on the separator and which has descended, as required. The separator is retracted in a forward translation and then raises toward its resting position at a level of the ejecting rollers.
During the descent of the table, a set of secondary forks, which have initially been integrated in the first set, descend owing to gravitational force in order to maintain a light pressure on the top of the batch prior to the batch being ejected. Moreover, above the ejecting carrier, a second pressing carrier or conveyor is permanently installed, which carrier is to apply a light holding pressure on the batch being ejected or removed. However, these applied pressures are low and become quickly inefficient as soon as movement with quicker acceleration is required.
The front stops are arranged together on a horizontal spindle which allows for adjusting their position according to the size of the boxes to be received. However, it is quickly evident that the device for driving the separator along the toothed rack can only be of a low force, which fact leaves the separator only a passive role of accompanist. The station then necessitates the use of a stronger pusher in order to eject the batch of boxes, which always consists of a slow, heavy and expensive member or element for the station.
Moreover, numerous flexible cams are arranged rotatably on an axle located at the level of the ejecting rollers. These cams regularly engage or hit the rear edge of each box in order to push it forward onto the pile. However, this device, as well as its coordination means, are very complicated for the little effect obtained.
Above all, all of the above-mentioned stations can only function at satisfaction with limited speed, due to the inertia of the complex mechanism used, the retractable fingers and pushers.